The performance with a prepared statement is clearly better.
4490914 0.09193658828735352
6791914 0.11825180053710938
10243426 0.24472475051879883
15420706 0.3097679615020752
23186626 0.4547543525695801
35291615 0.7077429294586182
53492990 1.0943055152893066
However inserting the next record of about 7 MB size just blocks without any error, without any timeout. The logs record myriads of these messages.
E0821 04:49:58.241580 18126 process_context.cc:180] SQL Error: Invalid Arguments. YQL value too long
INSERT INTO ybdemo.ugent(id, data) VALUES (?, ?)
Likely there is a way to to increase the maximum size of here. But this error must be propagated back to the client.